From: Esben Haabendal <esben@geanix.com> To: netdev@vger.kernel.org Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, "Andrew Lunn" <andrew@lunn.ch>, "David S . Miller" <davem@davemloft.net>, "Michal Simek" <michal.simek@xilinx.com>, "Petr Štetiar" <ynezz@true.cz> Subject: [PATCH net v2 1/4] net: ll_temac: Fix race condition causing TX hang Date: Fri, 21 Feb 2020 07:47:21 +0100 [thread overview] Message-ID: <c93e0f5ef92d2b17c04e256e32460e9dee1107e8.1582267079.git.esben@geanix.com> (raw) In-Reply-To: <cover.1582267079.git.esben@geanix.com> It is possible that the interrupt handler fires and frees up space in the TX ring in between checking for sufficient TX ring space and stopping the TX queue in temac_start_xmit. If this happens, the queue wake from the interrupt handler will occur before the queue is stopped, causing a lost wakeup and the adapter's transmit hanging. To avoid this, after stopping the queue, check again whether there is sufficient space in the TX ring. If so, wake up the queue again. This is a port of the similar fix in axienet driver, commit 7de44285c1f6 ("net: axienet: Fix race condition causing TX hang"). Fixes: 23ecc4bde21f ("net: ll_temac: fix checksum offload logic") Signed-off-by: Esben Haabendal <esben@geanix.com> --- drivers/net/ethernet/xilinx/ll_temac_main.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/drivers/net/ethernet/xilinx/ll_temac_main.c b/drivers/net/ethernet/xilinx/ll_temac_main.c index 6f11f52c9a9e..996004ef8bd4 100644 --- a/drivers/net/ethernet/xilinx/ll_temac_main.c +++ b/drivers/net/ethernet/xilinx/ll_temac_main.c @@ -788,6 +788,9 @@ static void temac_start_xmit_done(struct net_device *ndev) stat = be32_to_cpu(cur_p->app0); } + /* Matches barrier in temac_start_xmit */ + smp_mb(); + netif_wake_queue(ndev); } @@ -830,9 +833,19 @@ temac_start_xmit(struct sk_buff *skb, struct net_device *ndev) cur_p = &lp->tx_bd_v[lp->tx_bd_tail]; if (temac_check_tx_bd_space(lp, num_frag + 1)) { - if (!netif_queue_stopped(ndev)) - netif_stop_queue(ndev); - return NETDEV_TX_BUSY; + if (netif_queue_stopped(ndev)) + return NETDEV_TX_BUSY; + + netif_stop_queue(ndev); + + /* Matches barrier in temac_start_xmit_done */ + smp_mb(); + + /* Space might have just been freed - check again */ + if (temac_check_tx_bd_space(lp, num_frag)) + return NETDEV_TX_BUSY; + + netif_wake_queue(ndev); } cur_p->app0 = 0; -- 2.25.0
WARNING: multiple messages have this Message-ID (diff)
From: Esben Haabendal <esben@geanix.com> To: netdev@vger.kernel.org Cc: "Andrew Lunn" <andrew@lunn.ch>, "Michal Simek" <michal.simek@xilinx.com>, linux-kernel@vger.kernel.org, "Petr Štetiar" <ynezz@true.cz>, "David S . Miller" <davem@davemloft.net>, linux-arm-kernel@lists.infradead.org Subject: [PATCH net v2 1/4] net: ll_temac: Fix race condition causing TX hang Date: Fri, 21 Feb 2020 07:47:21 +0100 [thread overview] Message-ID: <c93e0f5ef92d2b17c04e256e32460e9dee1107e8.1582267079.git.esben@geanix.com> (raw) In-Reply-To: <cover.1582267079.git.esben@geanix.com> It is possible that the interrupt handler fires and frees up space in the TX ring in between checking for sufficient TX ring space and stopping the TX queue in temac_start_xmit. If this happens, the queue wake from the interrupt handler will occur before the queue is stopped, causing a lost wakeup and the adapter's transmit hanging. To avoid this, after stopping the queue, check again whether there is sufficient space in the TX ring. If so, wake up the queue again. This is a port of the similar fix in axienet driver, commit 7de44285c1f6 ("net: axienet: Fix race condition causing TX hang"). Fixes: 23ecc4bde21f ("net: ll_temac: fix checksum offload logic") Signed-off-by: Esben Haabendal <esben@geanix.com> --- drivers/net/ethernet/xilinx/ll_temac_main.c | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/drivers/net/ethernet/xilinx/ll_temac_main.c b/drivers/net/ethernet/xilinx/ll_temac_main.c index 6f11f52c9a9e..996004ef8bd4 100644 --- a/drivers/net/ethernet/xilinx/ll_temac_main.c +++ b/drivers/net/ethernet/xilinx/ll_temac_main.c @@ -788,6 +788,9 @@ static void temac_start_xmit_done(struct net_device *ndev) stat = be32_to_cpu(cur_p->app0); } + /* Matches barrier in temac_start_xmit */ + smp_mb(); + netif_wake_queue(ndev); } @@ -830,9 +833,19 @@ temac_start_xmit(struct sk_buff *skb, struct net_device *ndev) cur_p = &lp->tx_bd_v[lp->tx_bd_tail]; if (temac_check_tx_bd_space(lp, num_frag + 1)) { - if (!netif_queue_stopped(ndev)) - netif_stop_queue(ndev); - return NETDEV_TX_BUSY; + if (netif_queue_stopped(ndev)) + return NETDEV_TX_BUSY; + + netif_stop_queue(ndev); + + /* Matches barrier in temac_start_xmit_done */ + smp_mb(); + + /* Space might have just been freed - check again */ + if (temac_check_tx_bd_space(lp, num_frag)) + return NETDEV_TX_BUSY; + + netif_wake_queue(ndev); } cur_p->app0 = 0; -- 2.25.0 _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-02-21 6:47 UTC|newest] Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-02-19 10:53 [PATCH net 0/4] net: ll_temac: Bugfixes Esben Haabendal 2020-02-19 10:53 ` Esben Haabendal 2020-02-19 10:53 ` [PATCH net 1/4] net: ll_temac: Fix race condition causing TX hang Esben Haabendal 2020-02-19 10:53 ` Esben Haabendal 2020-02-19 10:54 ` [PATCH net 2/4] net: ll_temac: Add more error handling of dma_map_single() calls Esben Haabendal 2020-02-19 10:54 ` Esben Haabendal 2020-02-19 18:59 ` David Miller 2020-02-19 18:59 ` David Miller 2020-02-20 8:32 ` Esben Haabendal 2020-02-20 8:32 ` Esben Haabendal 2020-02-20 18:11 ` David Miller 2020-02-20 18:11 ` David Miller 2020-02-19 10:54 ` [PATCH net 3/4] net: ll_temac: Fix RX buffer descriptor handling on GFP_ATOMIC pressure Esben Haabendal 2020-02-19 10:54 ` Esben Haabendal 2020-02-19 10:54 ` [PATCH net 4/4] net: ll_temac: Handle DMA halt condition caused by buffer underrun Esben Haabendal 2020-02-19 10:54 ` Esben Haabendal 2020-02-21 6:47 ` [PATCH net v2 0/4] net: ll_temac: Bugfixes Esben Haabendal 2020-02-21 6:47 ` Esben Haabendal 2020-02-21 6:47 ` Esben Haabendal [this message] 2020-02-21 6:47 ` [PATCH net v2 1/4] net: ll_temac: Fix race condition causing TX hang Esben Haabendal 2020-02-21 6:47 ` [PATCH net v2 2/4] net: ll_temac: Add more error handling of dma_map_single() calls Esben Haabendal 2020-02-21 6:47 ` Esben Haabendal 2020-02-21 6:47 ` [PATCH net v2 3/4] net: ll_temac: Fix RX buffer descriptor handling on GFP_ATOMIC pressure Esben Haabendal 2020-02-21 6:47 ` Esben Haabendal 2020-02-21 6:47 ` [PATCH net v2 4/4] net: ll_temac: Handle DMA halt condition caused by buffer underrun Esben Haabendal 2020-02-21 6:47 ` Esben Haabendal 2020-02-22 0:05 ` [PATCH net v2 0/4] net: ll_temac: Bugfixes David Miller 2020-02-22 0:05 ` David Miller
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